Adopting a dog is admirable and should be encouraged, however, bringing poor Effie over from Greece to London might not have been the best idea.
I am from Greece and we do have quite a few strays, both in the cities and the islands (if I remember correctly Effie was rescued from an island), however most of them are well taken care of by the locals and many volunteering organizations try to gather and neuter them to curb the issue. Not saying that there aren't any instances of abuse and mistreatment, but I'd say that's a minority and most people try and care for the strays in their neighborhoods. Some cats and dogs are pretty much "neighborhood pets" and they live healthy, happy lives.
The whole "rescuing" the animal from a horrible life on a sunny, warm Greek island, to give her a better future in cold, gray London with an erratic owner just left a bad taste in my mouth when I first learned of her adoption story. The poor thing was probably more traumatized by being displaced and shipped to a different country to be given to a crying woman in the middle of the night like a hostage than from her life back on the island!
Obviously I don't know the circumstances behind Effie's adoption, but I think adopting locally from a shelter should be the first priority, either in Greece or the U.K, rather than shipping a live creature to you from abroad. There is a sort of savior complex hiding there that I just find a bit distatestful.